55s 



THE AMERICAN NATURALIST [Vol.L 



The hermaphrodites would then be designated as FFM 

 or simply as FH. It will be seen from the following dis- 

 cussion that the only formulation which will meet the 

 conditions is that which assumes the female to be a neutral 

 homozygote. 



In the above mentioned paper on the " Inheritance of 

 Certain Characters of Grapes" (Hedrick and Anthony, 

 1915) the authors have concluded that the results ob- 

 tained on inheritance of sex do not conform to the ex- 

 planation of sex inheritance dependent on one sex being 

 considered heterozygous and the other homozygous for 

 sex determiners. It appears, however, that by using the 

 hypothesis of partial suppression of sex determiners, the 

 condition in the grape would be in accordance with the 

 assumption of a homozygous condition for femaleness in 

 the functional females, a heterozygous condition for male- 

 ness and femaleness in the functionally male plants, and 

 a heterozygous condition for femaleness and hermaph- 

 roditeness in some of the hermaphrodites, while others 

 would be homozygous for the hermaphrodite determiners. 

 The authors based their conclusions upon the supposition 

 that the hermaphrodites bearing upright and those bear- 

 ing reflexed stamens were of a single type genetically, and 

 produced only hermaphrodites and no females when 

 crossed. This assumption seems erroneous. 



Using the formulae suggested above, let us apply them 

 to the data given by the authors, which are as follows : 



U X Us = 180 U + 47 R R X R 3 — 16 U -f 16 R 



U selfed = 673 U + 152 R R selfed = 94 U + 73 R 



U selfed = 18 U+ OR 



Total 871 U + 199 R Total 110 U + 89 R 



R atio 4.3U : 1R Ratio 1.2U : 1R 



RXU = 207U + 206 R 



?rmaphrodite female X pure male = 56 hermaphrodites + 51 i 



i bearing upright stamens which are usually functional. R r< 

 mphrodites bearing reflexed stamens which rarely produce fu: 



